GB2219011A - Child's sawing machine - Google Patents

Abstract

A sewing machine suitable for use by children has a main shaft 6 for reciprocating a needle 12 and a thread take-up lever 13, and a secondary shaft 17 for reciprocating a slide plate 20 driving a rotary hook and a feed dog 44. <IMAGE>

Description

SEWING MACHINE The present invention relates to a sewing machine suitable for use by children and having a drive mechanism which is simplified so far as possible while nevertheless permitting a reliable sewing operation.

Known sewing machines have generally been intended for use by adults and include a great number of parts.

Consequently they are expensive to manufacture and assemble. If the known machines are operated clumsily, damage may be caused or faulty operation may result.

They are therefore not suitable for use by children. On the other hand, sewing machines hitherto designed for children have generally been over- simplified and have not been reliable in operation.

A particular problem associated with designing a sewing machine suitable for use by children is to arrange for the movements of the needle, needle thread take-up lever and the rotary hook to be properly synchronised using simple mechanisms.

According to the invention a sewing machine comprises: a frame including a bed section, a main drive shaft, a vertically reciprocable needle and a needle thread take-up lever both being operated interlocked and-in'' synchronization with the main drive shaft, a secondary shaft interlocked with the main drive shaft, a slide plate supported for movement within the bed section, the secondary shaft being engaged with a base end of the slide plate, a rack formed on a projection on the slide plate, the rack being enmesh with a gear on a support shaft of a rotary shuttle including a rotary hook and a rotary bobbin case holder, said shaft being supported on the bed section, a tip provided on the rotary hook being rotatable in synchronism with the vertical movement of the needle and the thread take-up lever, and a cloth feeding mechanism operable by movement of the slide plate.

Preferably a sewing machine as claimed in claim 1, further comprising a plate provided with a feed dog projected through an opening in a throat plate, said plate being supported by guide pieces on the bed section so as to allow the plate to move vertically and horizontally, the bottom of the plate being provided with a pin engaging in a guide hole inclined the longitudinal axis of the slide plate, and angularly moveable plate being located on the top of said bed section so as to allow it to be engaged with projection provided on the slide plate when rotated, and the feed dog plate being engaged with said cam projections for producing upward movements, and a cloth sewing mechanism moveable in the longitudinal direction of the feed dog plate along said guide hole.

More preferably a sewing machine as claimed in claim 1, further comprising a guide slot formed longitudinally of the slide plate, said slot being widened at one end to form a substantially isosceles triangle, and arm arranged above the slot and having therein a hole arranged to register with a slot, a connecting rod engaging with the arm and displaceable with the arm and displaceable by a knob, the slot and hole cooperating to form a guide for the pin, whereby in one position of the arm forward stitching is formed, and in the other position of the arm, reverse stitching is performed.

In the drawings: Figure 1 is a perspective view illustrating the main parts of the proposed sewing machine within the housing of the main body indicated by chain lines, Figure 2 is a top plan view of a slide plate and related mechanism, Figure 3 is a vertical section through the parts shown in Figure 2, Figure 4 is a section taken on the line lV-1V in Figure 3, Figure 5 is an exploded perspective view of the bobbin and bobbin case.

Figures 7A to 7E show various stages of operation, Figure 8 is a view similar to Figures 7A to 7E showing further details, Figure 9 is a section through a line of stitching, Figure 10 is a graph to illustrate the relationships between various parts of the machine at the stages of operation indicated in Figures 7A to 7B, Figure IlA and Figure 11B are plan views of a modified cloth feeding mechanism, showing forward and reverse stitching respectively, and Figure 12 is an exploded perspective view of the cloth feeding mechanism shown in Figures IlA and 11B.

Referring to Figure 1, the body 1 of a sewing machine suitable for use by a child is shown in phantom lines to include a bed 2A, an upstanding pillar 2B at one end, and a cantilevered upper casing 2C projecting from the pillar. Housed within the pillar 2B is a motor 3 powered from an electric battery, the circuit of which includes a main on/off switch, not shown. A main shaft 6 extending through the pillar and casing 2C is provided at one end with a main gear 5 driven from the motor 3 by way of transmission gearing 4. The shaft 6 is provided at its other end with a link 8 articulated to a link 9 and having a pin 10 journalled in a slide lIA guided for movement on a vertical bar 11B. The slide llA carries a depending tubular needle support 11.A thread take-up lever 13 is pivoted to the link 9 about the axis of articulation of the link 8. The thread take-up lever has a tip which projects through a slot in the upper casing and has an eye 14 through which thread 50 passes from a reel 15A to an eye in the needle 12 which is fitted removably into the needle support 11. A support link 15 is journalled in the upper housing 2C upon pivots 15A.

The tip of the thread take-up lever moves in synchronism with the needle 12 and a rotary hook to be described subsequently.

The shaft 6 carries a crown gear 7 in mesh with a gear 16 on the upper end of a vertical secondary shaft 17 supported in the pillar 2B. The lower end of the shaft 17 carries a lever arm 18 from which projects a pin 19, as shown in Figure 3. The pin 19 is received within a slot 21 extending transversely of a slide plate 20 slidably supported within the bed 2A. A slot 22 extending longitudinally of the slide plate 20 receives a screw which is screwed into a boss projecting upwards from the base 48B of the bed 2A. The screw is provided with a washer 23 for retaining and guiding the slide plate. As shown in Figure 2, the plate 22 has a further longitudinally extending slot 22A. A rotary hook 30 has a support shaft 32 which passes through the slot 22A and is supported rotatably on the base 48B.A projection 24 extending alongside the slot 22A is formed with a toothed rack 25 on the side facing the slot. The rack meshes with gear teeth 33 formed on the shaft 32, so that reciprocation of the plate 20 under the action of the rotating link 18 causes the rotary hook 30 to rotate alternately in opposite rotational directions through predetermined angles.

The central portion of the slide plate 20 overlies an angularly reciprocable cam plate 46 having upstanding projections 47 at its ends which form cam surfaces. The slide plate has depending projections 27, 28 capable of contacting the cam plate 46 to turn it through a limited angle as the slide plate nears the end of its travel in either direction. A pair of guides 41 project upwards from the base 48B and have grooves 42 for receiving an upstanding feed plate 43 provided on its upper edge with a feed dog 44. The feed plate 43 is free to move vertically and horizontally within the grooves. The upper surface of the bed is formed wholly or in part by a removable throat plate 48A. The feed dog is capable of projecting through an opening 49 in the throat plate 48A when the plate 43 is in an upper position. A pin 45 projecting from the lower edge of the plate 43 enters an angled slot 26 in the plate 20. It will be appreciated that as the plate 20 reciprocates, the cam slot 26 causes the plate 43 to reciprocate in the direction transversely of the plate 20, while arcuate movement of the plate 46 causes the plate 43 to rise and fall. The feed dog therefore rises, moves to the left, descends, moves to the right, thereby transporting fabric intermittently beneath the needle.

The rotary hook 30 has a pointed tip on its outer peripheral surface and a cavity which receives a shuttle body 34 such that the outer peripheral surface of the shuttle body is in contact with the inner peripheral surface of the rotary hook. The shuttle body 34 has a cavity which receives a bobbin case holder 35 which accommodates a bobbin 36 providing a bobbin thread 37. A keep plate 39 fixed on the bed section 2A has a tip portion which engages the top of the shuttle body 34 to prevent it from rotating with the hook.

Figure 10 illustrates the relative movements of the needle 12, thread take-up 13, the hook 30 and the feed dog 44 during a cycle of operations. The movements are related to the rotational positions of the main drive shaft 6 which are plotted along the x-axis. The angular or linear positions of the part in question as the case may be are plotted along the y-axis. Curve 12A represents the vertical position of the tip of the needle 12 relative to the throat plate 48 which is indicated by the x axis. The curve 13A is related to the height of the tip of the needle thread take-up lever 13 above the throat plate, the lowest point on the curve representing a height of the thread eye which is 48mm above the throat plate, and the highest point on the curve representing a height of the eye of 139mm therefrom. Curve 30A represents the rotational position of the rotary hook 30.

In the figure, the tip 31 of the hook is related to a line between the needle 12 and the axis of the bobbin 30, this reference line being represented by the x axis.

Counterclockwise rotation of the hook 30 is indicated by a negative slope of the curve 30A.

The curve 44A represents the vertical position of the feed dog 44, horizontal movement of the dog in the cloth advancing direction being indicated by the letter X.

The position of the rotary hook and associated parts at the points in time indicated by the letters A to E in Figure 10 are shown in Figures 7A to 7E respectively.

In Figure 7A, the needle 12 is at its lowest point so that the length of thread 50 passing through the eye of the needle is below the cloth resting on the throat plate. The rotary hook has just commenced movement in the counterclockwise direction. The thread take-up lever 13 is beginning to move downwards so that a loop 50A of thread 50 begins to form and is located just ahead of the tip 31 when the parts reach the position shown in Figure 7B when the tip 31 crosses the reference line, as indicated by the curve 30A passing through the x axis.

The needle begins to rise as the hook catches the loop and rotates through an angle 140e in the clockwise direction into the position shown in Figure 7C. The take-up lever continues to descend to allow the loop to enlarge and the needle continues to rise. Figure 7D shows the arrangement when the needle is at its uppermost position and the tip 31 has just passed its point of maximum rotation in the counterclockwise direction and is beginning to return in the clockwise direction. The loop 50 is slipped off and cooperates with the bobbin thread 37 ready to form a stitch. As shown in Figure 7E, the needle is descending and the take-up lever at its highest position so that the thread 50 is tensioned to stitch the bobbin thread 37 and the cloth, see Figure 9.When the parts are in the positions shown in Figure 7D and Figure 7E, the feed dog is in its raised position and forming a feeding operation while the needle is in a position 5mm above the throat plate. The feeding movement of the feed dog ceases when the needle moves down to a position near the top of the throat plate. The tip of the rotary hook is at a position of 130 from the reference line.

Figure 8 shows the parts in positions similar to those represented in Figure 7E but omitting the cloth so as to show the feed dog.

Figures 11 and 12 show a modification which permits reverse stitching. The drive mechanism is identical to that previously described except that the slide plate 20 has an elongate slot 26C widened into an isosceles triangle 26B at one end. Mounted above the slot is an arm 51 having a pivot 53 which is received within a hole in the slide plate 20. The arm 51 has a shaped slot 52 which overlies the slot 26C projections 20A on the slide plate 20 serve as stops to limit angular movement of the arm 51 about its pivot 53.

A rod 55 is cranked so that its end 56 forms a channel which receives a post 54 upstanding from the free end of the arm 51. The other end of the rod 55 is formed into a vertical contact piece 57 and a portion 55A supported in the main body. A knob 59 supported in the main body for sliding movement may be made to bring an angled portion 60 to bear on the contact piece 57 in opposition to a spring 58. Sliding the knob towards the left turns the rod in the counterclockwise direction about the fulcrum 55A while sliding the knob towards the right allows the rod to be restored in the clockwise direction by the spring 58. The portion 56 with a rod accordingly positions the arm 51 in the position shown in Figure llA or the position shown in Figure llB. The slots 52 and 26 cooperate to define a track for the projection 45 of the feed dog, whereby the feed dog feeds in the direction N or the direction M as indicated in these figures, depending upon whether the slot is defined in part by the edges 26B and 52A, or 26A and 52B respectively.

With the parts arranged as shown in Figure llA, forward stitching may be performed, whereafter the knob 59 may be depressed and reverse stitching carried out.

Claims (4)

1. A sewing machine comprising: a frame including a.bed section, a main drive shaft, a vertically reciprocable needle and a needle thread take-up lever both being operated in interlocked relationship and in synchronization with the main drive shaft, a secondary shaft in interlocked relationship with the main drive shaft, a slide plate supported for movement within the bed section, the secondary shaft cooperating with a base end of the slide plate so as to cause the slide plate to reciprocate, a rack formed on the slide plate, the rack being enmesh with a gear on a support shaft of a rotary shuttle including a rotary hook and a bobbin case holder, said shaft being supported in the bed section, a tip provided on the rotary hook being rotatable in synchronism with the vertical movement of the needle and the thread take-up lever, and a cloth feeding mechanism operable by movement of the slide plate.

2. A sewing machine as claimed in claim 1, further comprising an upstanding feed plate provided with a feed dog capable of projecting through an opening in a throat plate of the bed section, said feed plate being supported by guide pieces on the bed section so as to allow the feed plate to move vertically and horizontally, the bottom of the feed plate being provided with a pin engaging in a guide hole inclined to the longitudinal axis of the slide plate, an angularly moveable cam plate provided with cam projections, the angularly moveable plate being located so as to allow it to be engaged with a projection provided on the slide plate when rotated, and the feed plate being engaged with said cam projections in order to move the feed plate vertically, and a cloth sewing mechanism moveable in the longitudinal direction of the feed plate.

3. A sewing machine as claimed in claim 1, further comprising a guide slot formed longitudinally of the slide plate, said slot being widened at one end substantially to form an isosceles triangle, an arm arranged above the slot and having therein a hole arranged to register with the slot, a connecting rod engaging with the arm and displaceable by a knob, the slot and hole cooperating to form a guide for the pin on the feed plate, whereby in one position of the arm forward stitching is performed, and in the other position of the arm, reverse stitching is performed.

4. A sewing machine substantially hereinbefore described with reference to and as illustrated in Figures 1 to 10, both Figures 1 to 10 as modified by Figures 11 and 12 of the accompanying drawings.